1. Field of the Invention
This present invention relates to an image projecting apparatus, especially to a three-dimensional image projecting apparatus.
2. Description of the Prior Art
People utilize their two eyes to look at objects, to determine the distance by objects' angles, and to generate three-dimensional perception. Therefore, although both the left and right eye look at the same object, the visual angle of the two eyes are different, thus generating visual angle discrepancy between the two eyes. The visual angle difference between the left and right eye is bigger when the object is closer, and the visual angle difference between the left and right eye is smaller when the object is farther; the visual angle difference between the left and right eye is almost zero when the two eyes look at remote object in parallel.
The theorem of three-dimensional images of the prior art is to simulate the visual angles of the two eyes of humans by using two cameras to shoot simultaneously and then project the images simultaneously by two projectors; one projector simulates the image which is observed by the left eye, and the other projector simulates the image which is observed by the right eye. The images which are simulated by the two projectors are projected onto the same screen by utilizing the synchronization system, and the different images of the left and right eye are separated by utilizing polarization glasses which can filter horizontal and vertical light; therefore, the effect of a three-dimensional image can be shown.
Because the polarization glasses can filter horizontal and vertical light, the glasses which are worn by audience are made from two different polarization glasses, and the two same glasses are set in front of the two projectors; in this way, although the images which are projected by the two projectors look superimposed for the human eyes, the image of the projector with horizontal polarization can only be seen by the one side of the glasses with horizontal polarization, and the image of the projector with vertical polarization can only be seen by the other side of the glasses with vertical polarization. In this way, the different images can be seen by the left and the right eyes to generate the three-dimensional image; this system must use the non-depolarizing screen to achieve these effects.
Because of the low production cost of the polarization glasses, it is suitable to be used in venues for business, such as three-dimensional movie theater. Because the image is projected by utilizing two projectors synchronously, the quality and the luminosity of the image are better; this is the method with the best image quality to watch three-dimensional images by glasses.
However, because in the prior art two projection devices and a synchronization system are used, the cost is higher, and it is not easy to carry; also, because two projection devices must be used, the step of aiming the two projectors, which makes two images of the two projectors project on the same place of the screen, needs to be done before the image is projected, and then the three-dimensional image can be generated correctly.
Therefore, the main objective of the invention is to provide an image projecting apparatus to overcome the above problem.